Field of the Invention
The present invention relates to skin treatment devices for application of electromagnetic radiation to the skin, and in particular to hand-held devices that can be used in a wet environment. The invention is for example applicable for removal of hair by application of localised energy to destroy or damage the hair follicle or root, thereby preventing re-growth.
Description of the Related Art
Light-based skin treatment devices are increasingly used for various forms of personal care and therapeutic treatments. Such treatments can include hair removal, skin rejuvenation, acne treatment, pigmentation removal and the like. In addition to treatment in the visible spectrum, other regions of the electromagnetic spectrum are also used, including the infra-red, ultraviolet and radio frequencies. Hereinafter, reference to light is not intended to be limited to the visible spectrum unless otherwise specified.
Hair removal is of particular importance in the context of personal care for both men and women. Removal can take place temporarily by shaving, epilating and waxing, or more permanently by high energy techniques such as laser removal and the use of intense pulsed light (IPL) flash lamps. High energy techniques are frequently used by professional cosmetic technicians in dedicated salons. The devices are relatively complex, and care and experience may be required to avoid injury to a patient. One device is known from US 2008/139901 which describes a photo-cosmetic device usable for various treatments. The device includes a base station and a handpiece coupled by a cable. The handpiece includes a treatment head and a source of electromagnetic radiation and can be provided with active or passive cooling to prevent damage to the head or to the patient's skin.
Recent devices have also been developed for personal use. Such devices are often simpler than professional quality models and may operate at lower power levels and/or may have a smaller treatment head. Nevertheless, they can be effective in temporarily or even permanently removing hair if used over a period of time. A device of this type has been described in WO2004/047921, which includes a hand-held housing incorporating a radiation source and a radiation filter. The radiation filter is designed to adsorb harmful wavelengths of radiation and allow those wavelengths to reach the skin that are required to perform the desired treatment. Due to the significant energy density of the radiation, the filter can become extremely hot. A cooling system is provided in order to avoid overheating.
Although the above mentioned devices have made such forms of light-based skin treatment accessible for the non-professional consumer, the mode of use of these devices remains limited. Consumers increasingly wish to perform grooming and skin-care activities while bathing or showering, but the existing hand-held devices are unsuitable for use in a wet environment and could not be used underwater without damage to the device or danger to the individual. It would therefore be desirable to provide an improved device which increases the flexibility of use and which better enables a user to safely integrate hair removal activities into their lifestyle. At the same time, the improved device should provide sufficient cooling of the source of electromagnetic radiation arranged in the housing of the device. The same applies to other personal skin-care treatments such as skin rejuvenation, wrinkle treatment and the like.